Let me restate my position, since there appears to be some
confusion concerning what I was trying to get across.
First, CSI is defined not only for instances meeting the
universal small probability bound of 500 bits, but can be
justified for lower complexity values as well (see Dembski's
"The Design Inference", section 6.5, "Local and universal
small probabilities").
Second, natural selection is noted to be able to accumulate
information none other than William Dembski (see his 1997 NTSE
paper, "Intelligent Design as a Theory of Information").
With these two pieces of information, it becomes apparent that
any instance identified as showing natural selection in
operation also shows natural selection as the cause of an
event with the property of CSI. (I don't want to bother with
the semantic arguments over whether CSI is "generated" or
"transformed" in such cases; it makes no difference to the
point.)
The only point in question is "how complex is the CSI which
natural selection is known to cause?" We know that the
information is specified, since the side information that
tells us what selective pressure was operative enables us
to produce a specification. It is only the complexity
measure that is at issue.
Natural selection, though, is notoriously difficult to
empirically isolate as a mechanism of action. The level of
evidence needed to both implicate natural selection and to
exclude genetic drift is high. Indirect evidence, such as the
presence of linkage disequilibrium in a population, serves as
an indicator of the action of natural selection, but
biologists tend to want to see a clear relation between a
cause of selection and an effect in distribution of traits in
a population.
Because of this problem in unambiguous identification of
natural selection in action, our examples of natural selection
as a causal process are also limited. Nevertheless, there do
exist examples. Various antibiotic resistant strains of
bacteria, finch beak size changes, and nylon-digesting bacteria
all show natural selection in action.
So, what are the complexity levels associated with each of
these? It is a good question, and one that must await some
clarifying explication from William Dembski. Some time ago,
Paul Nelson mentioned that Dembski was examining known
instances of natural selection with the intent to show that
all such known cases were caught at the HP or IP nodes of his
explanatory filter. That is one reason that I pointed out in
my review of TDI that such an exercize does not exclude
natural selection in principle from causing events with higher
complexity levels. However, it would be interesting to see
what Dembski's completely worked-out calculations for these
cases look like.
It is especially interesting to consider the effect that use
of a local small probability would have upon classification of
an event. In that case, fewer events would go into the IP bin
and more would go into the DES bin. Further, if one excludes
from the analysis the putative causal hypothesis (as Dembski
does for his informal examples), fewer events would be found
to go into the HP bin, and more would go into the DES bin.
The Explanatory Filter and its instantiation as the Design
Inference does not yield a static mapping of events into
categories. Instead, which events go into which categories
changes with changes in the background knowledge applied. Nor
does the DES bin act like a black hole; analysis of the same
event with more complete information can move categorization
from DES to HP or IP.
What about instances of adaptive features for which we do not
have overwhelming evidence that natural selection in
particular caused them?
Taking it as possible that adaptive features of organisms are
designed and installed by an intelligent agent via a mechanism
other than natural selection means that we cannot use as
examples of the efficacy of NS those phenomena in question,
unless and until we have in hand the same kind of evidence
that suffices for Galapagos finch beak changes. This may
simply never be available. But if all that is available for
the alternative hypothesis of ID is the simple fact of
CSI_500, then I doubt that many biologists will feel compelled
to exclude natural selection as a live possibility on those
grounds alone.
What we are then left with is an argument that we should
exclude from consideration a mechanism of generating solutions
that we can observe to happen in modern populations and which
produces CSI at lower complexity levels during our brief and
spotty periods of observation in favor of a mechanism which
has no independent evidence of operation and which is not
currently observable. (That is, the intelligent agent
putatively responsible for the biological system under
question is not known from current observation or from
independent evidence of the period in question.) I think that
such an argument will find it rough going to convince
knowledgeable people of its merits.
We should do the calculations to determine the CSI level of
various examples of NS in action, or general "descent with
modification" in action. Things like bacteria digesting nylon
with novel enzymes or the emergence of the impedance-matching
apparatus of the mammalian middle ear need to be explored
quantitatively. A spread of CSI levels may indicate an
approach to the CSI_500 level that Dembski sets, and indicate
that no essential qualitative difference exists between the
capability of natural evolutionary algorithms and intelligent
agency.
It would focus the discussion wonderfully if either Paul or
Bill would provide a worked example of running some scenario
involving natural selection through the Design Inference. We
are urged to "do the calculation" at the end of TDI, but there
seems to be a dearth of serious examples with a complete set
of calculations per each.
Every example of natural selection known produces CSI at some
local small probability level (cf. TDI, section 6.5). In cases
where the causal process is not known with certainty, finding
that the event in question has CSI at some high level is
entirely ambiguous concerning whether natural selection or
intelligent agency is the cause.
Wesley
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